RFR: 8373613: PEXT/PDEP intrinsics cause performance regression on AMD pre-Zen 3 CPUs [v2]

[Alessandro Autiero]

On Tue, 24 Feb 2026 22:52:34 GMT, Jasmine Karthikeyan <jkarthikeyan at openjdk.org> wrote:

>> Alessandro Autiero has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - updated copyright year
>>  - added fast_bmi2 CPU feature to CPUInfoTest
>
> src/hotspot/cpu/x86/vm_version_x86.hpp line 458:
> 
>> 456:     decl(AVX10_2,           avx10_2,           64) /* AVX10 512 bit vector ISA Version 2 support*/ \
>> 457:     decl(HYBRID,            hybrid,            65) /* Hybrid architecture */ \
>> 458:     decl(FAST_BMI2,         fast_bmi2,         66) /* Native Hardware support for PEXT/PDEP BMI2 instructions */
> 
> You'll also need to add `"fast_bmi2"` to the list of well-known CPU features in [CPUInfoTest.java](https://github.com/openjdk/jdk/blob/master/test/lib-test/jdk/test/whitebox/CPUInfoTest.java), as otherwise it would assert when encountering an unrecognized feature.

I've fixed both issues, thanks for the input.

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PR Review Comment: https://git.openjdk.org/jdk/pull/29809#discussion_r2854084027